Key takeaways
- The crown is the first defense against rain
- Cracks let water into the brick and flue
- Small cracks may be sealed, large ones need rebuilding
- A cap adds extra protection
What a crown does
The crown is the slab of concrete or mortar on top of the chimney that caps the brick and slopes water away from the flue. It is the main shield against rain.
Over time, freeze and thaw cycles and shrinkage cause cracks, and water gets into the brick and mortar below.
How to spot trouble
Look for cracks, crumbling edges, missing chunks and a crown that sits flat with no overhang. Check for white stains and loose mortar on the upper bricks, which are signs of water getting in.
A crown made from mortar, rather than a proper concrete mix, is more prone to cracking.
Repair or rebuild
Small, shallow cracks can sometimes be sealed with a product made for crowns. Large or deep cracks usually mean the crown should be removed and rebuilt with a sloped top, a drip edge and a proper mix.
Adding a cap on top of the flue helps keep out rain, leaves and animals.
Related services
Quick answers
Can I seal a chimney crown crack myself?
A crown sealer can help on small, shallow cracks, but it is a patch, not a fix. If the crown is crumbling, rebuilding it is the lasting answer.
What is the difference between a crown and a cap?
The crown is the masonry slab around the top of the chimney. The cap is a metal cover over the flue opening that keeps out rain and animals.
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